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I was wondering about the industry standard for building cabling of Cat5e from the elctrical closet to the end user. More specificly from the patch panel to the wall plate.

I was told at some point that the ends on your link from the patch panel to the wall plate should be of the same type. I.E. 110 punch down socket of brand X going to another 110 punch down socket of the same brand X and not to exceed a 280 foot cable length. This way you have a nice neat cabling job, and any patch cables you use shouldn't exceed 10 foot in length so you'll never go over your 300 foot limit.

I was working at a place that didn't want to follow that method all the time. They instead would run a cable (less than 280ft) from the 110 punch down patch panel to the user but would instead pull the cable out of the wall through the wall plate and terminate with a RJ45 plug.

Aside from it looking cheesy, what are other problems you could encounter from this type of cable run? I was thinking that you might have impedence mismatches going from brand X 110 punch down socket to a brand Y plug that could possibly increase errors on longer runs? You would also have possible cable failures as the patch to wallplate cable typically would be solid core and be more prone to breakage from all the movement at the wall/user transition.

Am I just being paranoid about this or am I correct about my misgivings?

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    \$\begingroup\$ My guess is that since there's fewer connectors in the transmission path, the signal integrity will initially be better. The problem is probably if someone damages the exposed part of the cable by running a chair over it or moving a desk foot on top of it, you'd have to reterminate instead of just throwing away and replacing a patch cord. \$\endgroup\$ – The Photon Aug 9 '12 at 23:07
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    \$\begingroup\$ Reminds me of a saying a colleague liked to use: "Penny wise, pound foolish". You save yourself some money not installing the wall sockets, but in the long run you'll spend a small fortune troubleshooting and replacing cables. \$\endgroup\$ – jippie Aug 10 '12 at 7:19
  • \$\begingroup\$ I must say I am happily reassured that everyone else is seeing that it is a fault waiting to happen just as I have. \$\endgroup\$ – Chef Flambe Aug 10 '12 at 21:37
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The big problem with this is that in wall cabling isnt designed to be flexed repeatedly. It's more rigid to help running it through the walls. It will eventually break from being moved around too much. And when it breaks, it will be hard to repair.

Patch cables are usually made of stranded wire and designed to be more flexible. They are also cheap and easy to replace when they break.

Brands dont matter much as long as they are reputable and of decent quality. Typically you go from a punch panel in the network room to a wall faceplate in each office.

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From an electrical perspective, there's no problem with what you describe. I'm not familiar with '110 punch down sockets' except I just looked it up on Google images so I now vaguely know what it is. But in any case, in order to work they must provide a connection between twisted-pair transmission lines with low loss and low back-reflection. The characteristic impedance of the system is entirely set by the cable, and connectors from any brand will have to match that. Their other characteristics are purely mechanical. So there's no reason to worry about using the same brand connector or socket at both ends of the line --- except not to use poor-quality parts at either end.

And, each connector in the circuit will add some loss and back-reflection. So minimizing the number of connectors will actually improve the signal integrity.

But of course, from a maintenance and reliability perspective what you describe is a disaster waiting to happen. Any damage to the exposed part of the cable will have to be repaired by re-terminating the cable instead of just replacing a low-cost patch cord. Diagnosing a bad connection may also be more difficult (maybe needing a TDR instead of just swapping patch cables until you find the faulty one).

Also, see Grant's answer to confirm your suspicion of differences in cable manufacture that make cable designed for in-wall installation unsuitable for use in an exposed location.

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  • \$\begingroup\$ My main thoughts about using the same brand is that you never have an exact 50 ohm match. It's usually within 2-3 ohms either way (from what I've seen on a few spec sheets). If you use Brand Y and they are consistantly at 52 ohms and Brand X is at 48 ohms then mixing them will give you a greater mismatch than if you just use Brand Y on both ends. I'm just speculating about this and figured that must be the reasoning as to why I was originally told to use the same connectors on each end. \$\endgroup\$ – Chef Flambe Aug 10 '12 at 21:35
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    \$\begingroup\$ 1. The type of mismatch caused by a connector is usually capacitive or inductive rather than real. 2. Even in your scenario, either a 48 Ohm load or a 52 Ohm load on a 50 Ohm line causes about 2% reflection, but with opposite phase. Whether the net effect of the near end reflection and far end reflection being opposite signs causes a greater or lesser total reflection depends entirely on the length of the line. Changing the line length by 10 ft will entirely change whether its better to have the two reflections matched or opposite. \$\endgroup\$ – The Photon Aug 11 '12 at 17:46
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No need to worry. You can check cable running inside the wall with cable verification tools. These tools can check cables inside the wall also and will guide you to the particular point of cable breakage or ant other issue. Also you can diagnose bad cable connection.

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I think you are mostly being paranoid. Yes solid core cable is more vulnerable to stress through repeated flexing than stranded "patch" cable but unless you are moving things arround all the time then it shouldn't be a massive problem.

If you do crimp on plugs make sure you buy/use the right ones. Plugs designed for solid core cable are different from ones designed for stranded core cable and you can get unreliable connections if you use the wrong one. Some plugs do claim to be suitable for both but I don't know how well these work in priactice.

In terms of signal integrity the general rule is the less connections the better and stranded cable is slightly lossier than solid but unless you are pushing the length limits it shouldn't matter much.

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  • \$\begingroup\$ This is three years after the question was originally asked (and it's not a particularly good one anyway). It already has an accepted answer. This answer adds little that hasn't already been said. \$\endgroup\$ – David Oct 30 '15 at 22:26

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